Xerographic machine



p 1, 1964 H. E. CLARK ETAL 3,

XEROGRAPHIC MACHINE Filed May 1, 1961 FIG] DEVELOPER TERMINAL VELOCITYVS PLATE ANGLE v= DEVELOPER TERMINAL VELOCITY, m/sac OF across INVENTORSO HAROLD E. CLARK GEORGE R. MOTT 5 5 BY ROBERT w. GUNDLACH e PLATEANGLE, DEGREES- A 7" TORNE Y United States Patent 3,146,688 XEROGRAPHICMACHINE Harold E. Clark, Penfield, George R. Mott, Rochester, and RobertW. Gundlach, Victor, N.Y., assignors to Xerox Corporation, a corporationof New York Filed May 1, 1961, Ser. No. 106,656 4 Claims. (Cl. 95-1.7)

This invention relates to xerography, and more particularly, to improvedxerographic copying machines and to improved developing methodstherefor.

In a common form of xerognaphy, a uniform electrostatic charge is placedon the photoconductive insulating layer of a xerographic plate, anelectrostatic latent image is formed on the plate through exposure to anoriginal subject or pattern of light and shadow, the latent image ismade visible through the selective attraction of black powder or othermaterials, and the developed image is then generally transferred to asheet of paper or other support. Various forms of apparatus are knownfor carrying out these process steps in a mechanical or automaticfashion.

Generally commercial apparatus embodying automatic flow from one processstep to another includes what has become known as cascade developmentand automatic commercial equipment typically also includes a cylindricalxerographic plate. Cascade development employs cascade developercomprising generally carrier particles adapted to roll or cascade acrossthe surface to be developed bearing toner particles electrostaticallyadhering but adapted to deposit through release from the carrierparticle to charge patterns on the surface to be developed. Thedeveloper is flowed or cascaded across the surface to a point along thecircumference of the cylindrical plate whereat the cascading developerflows away from the plate because of inertia and gravitational pull.Inherent in all known commercially available apparatus is non-uniformityin the velocity of the developer as it passes across the cylindricalplate. Velocity non-uniformity results in non-uniform development frompoint to point during passage across the plate and in addition if thevelocity of the developing material becomes too high, a scrubbingor'similar action takes place so that deposited developer conforming tothe image to be developed is actually removed from the plate rather thandeposited in accordance with the basic objective of any developingsystem.

This invention is concerned with a novel form of xerographic apparatuswhich is simple, compact and capable of yielding unusually dense andhigh quality images. This invention is also concerned with a noveldeveloping arrangement for improving xerographic development.

It is accordingly an object of the present invention to provide improvedautomatic xerographic equipment.

It is a further object to provide improved xerographic developmentapparatus.

FIG. 2 is a graph relating developer velocity to xerographic cascadedevelopment methods.

These and other features and objects of the invention will be apparentfrom the following description and from the drawings in which:

FIG. 1 represents a partly schematic sectional view of an embodiment ofxerographic copying apparatus according to the invention; and

FIG. 2 is a graph relating developer velocity to xerographic plateinclination.

Referring to FIG. 1 of the drawings, the apparatus is seen to include apair of axially rotatable cylindrical elements and 11 about which issupported a xerographic plate 12 in the form of an endless flexiblebelt. The upper portion of the belt in this embodiment is in- 3,146,688Patented Sept. 1, 1964 clined at an angle of about 19 degrees from thehorizontal. Plate 12 comprises a web of strong, flexible, and,preferably electrically conductive material 8 such as a strip of coldrolled aluminum, brass or steel a few thousandths of an inch thick or ametallized plastic web such as aluminized polyethylene terephthalate.Plate 12 in this embodiment is illustrated as coated on its outersurface with a thin layer of a photoconductive insulating material 7.Any of the photoconductive insulating materials known in connection withxerographic plates which are capable of being flexed without destroyingtheir usual plate characteristics may be employed, including but notlimited to, a thin layer of vacuum deposited vitreous selenium or a thinlayer of zinc oxide in an insulating resin binder. Selenium and manyother photoconductive insulating materials coated on a flexible supportmay be repeatedly bent around a radius of a few inches without crackingor flaking from the support and Without losing xerographicefiectiveness. It is also possible to substitute for the endless plate12, as shown, two or more flexible sheet-like xerographic plates whichare connected to each other in an end-to-end relationship by coilsprings or the like or coated and uncoated areas intermittently alongthe surface of the conductive material 8. As will be apparent from afurther description of the operation of the machine, such other plateswill function in the same manner as a truly continuous plate and suchstructures are intended to be encompassed by the term endless flexiblebelt as used in the specification and claims.

A. motor 13, operated by timer 9, is provided to rotate cylindricalelement 10 and thereby to move xerographic plate 12 in the directionshown a suflicient distance so that a region of the plate lying betweencylindrical elements 10 and 11 along the lower section of the endlessloop is transferred to a position between elements 10 and 11 along theupper portion of the loop and vice Positioned adjacent and beneath plate12 and between cylindrical elements 10 and 11 is a full frame coronacharging device 14 which is connected to a high voltage power supply 15.This device generally comprises a grid of fine wires positioned adjacentand parallel to plate 12 and is more fully described in U.S. Patent2,932,742. By activating high voltage power supply 15, a large area ofplate 12 corresponding to charging device 14 is brought to a uniformhigh potential of the order of several hundred volts as is well known inthe xerog-raphic art. Exposure apparatus is provided to project ontoplate 12 and through charging device 14 a pattern of light and shadowcorresponding to an original subject to be reproduced. Because thefunctional area of charging device 14 consists only of a set of veryfine Wires, it is possible to effect exposure through charging device 14without objectionable shadows or the like being recorded. The imageprojection apparatus includes a copy box 16 including a glass platen 17on which may be laid the original copy such as, for example, a book 18.Illumination is provided by two or more lamps 19 which are set intoreflector plates 20 of polished aluminum or the like. The combination oflamps 19 and reflector plates 20 provides a highly uniform degree ofillumination over the original subject such as book 18. Light scatteredfrom book 18 is reflected by a first mirror 21 through a lens 22 whichthen focuses an image of book 18 onto xerographic plate 12 throughreflection at the surface of a second mirror 23. In accordance withknown xerographic principles, the projection of a pattern of light andshadow on the charged surface of xerographic plate 12 causes selectivecharge dissipation resulting in the formation of an electrostatic latentimage.

In normal operation the high voltage power supply 15 is first energizedfor a short time to uniformly charge plate 12 and lamps 19 are thenenergized for a short time to form an electrostatic latent image onplate 12. Following exposure, motor 13 is then briefly energized to moveplate 12 through about /2 of a complete rotation so that the areabearing the electrostatic latent image is now along the upper portion ofthe endless loop formed by plate 12 rather than along the lower portion.Image development is effected while the latent image bearing portion ofthe plate is in the upper position by a development apparatus which willbe described hereinafter. While development is being carried out asecond latent image may be formed at the lower portion of plate 12. Whenplate 12 is next advanced, the developed image area passes a transferand a cleaning station before returning to the charging and exposureposition where it is ready for further reuse. The transfer stationcomprises a pair of rollers 24 which urge a web 25 of paper or the likeagainst plate 12 and a corona charging device 26 positioned betweenrollers 24 and adapted to apply an electrostatic charge to the back ofpaper 25 thereby transferring a developed powder image from plate 12 topaper 25. A cleaning station may comprise an axially rotatable fur brushpositioned in lightly touching contact with plate 12 and adapted to bedriven by a motor or the like, not shown. Brush 27 removes any residualdeveloper powder from plate 12 and thereby permits the plate to beindefinitely cycled between the chargeexpose position and the developingposition.

It is a feature of the apparatus as thus far described that it utilizesthe so-called full frame method of image exposure rather than anexposure system adapted to continuous motion of the plate. Since each ofthe original subject, the optical system and the xerographic plate arestationary during exposure, there is no possibility of image resolutionbeing degraded by vibration or lack of synchronism as may occur in amoving system. Additionally, the full frame method of image exposurepermits the employment of much simpler apparatus than does a movingsystem. At the same time, however, it is possible, in accordance withthe present invention, to retain the simplicity and rapidity of imagedevelopment associated with rotary xerographic machines which employmoving exposure. Further, development according to the present inventionis more efficient and yields denser images than previous methodsemployed either with flat or cylindrical xerographic plates.

The development system includes a supply hopper 28 which is positionedabove xerographic plate 12 and which contains a supply of xerographicdeveloper 29 which may comprise any of the well known types of cascadedeveloper material. generally comprises a mixture of very finely dividedpigmented particles known as toner, generally having a diameter in therange of a few microns, mixed with much larger particles known ascarrier. Toner and carrier have triboelectric properties such that theyelectrify each other and such that the toner particles are adherent uponthe carrier particles or beads. Xerographic developer materials of thistype enjoy wide commercial use and are available from I-Ialoid XeroxInc., Rochester, New York. Supply hopper 28 includes a gate 30 whichcontrols the flow of developer into a chute 31 which terminates in acurved section 32. The effect of chute 31 and curved section 32 is todirect developer 29 approximately tangentially against xerographic plate12 in a downward direction and at a velocity determined principally bythe height of chute 31 and to a lesser extent by the inclination ofchute 31 and the radius of curved section 32. Chute 31 may either beinclined somewhat in the direction shown or vertical, or inclined in adirection opposite from that shown. The illustrated configuration,however, is believed to yield the most compact machine arrangement. Thedeveloper discharged by curved section 32 flows downwardly over thesurface of plate 12 and is caught in collection hopper 33 after flowingover the end of plate 12.

As is well known, developer 2 The developing apparatus as heretoforedescribed may be used for manual operation but is adapted to automaticoperation through utilization of conveyor 34 driven by a motor notshown, to return developer from hopper 33 to hopper 28 together withsolenoid 35 or the like to operate gate 30 and thereby control the flowof developer over plate 12.

As developer 29 flows over plate 12, the toner, in accordance with knownprinciples of xerography, is selectively detached from the carrierparticles and attached to the xerographic plate by the electrostaticlatent image thereon, thus forming a visible developed image on theplate. Additionally, the developer flowing over plate 12 is acceleratedor retarded toward the terminal velocity corresponding to the particularinclination of the plate. The terminal velocity is that velocity whichwould ultimately be reached by the developer if the xerographic platewere of indefinite length. It is, of course, also that velocity at whichthe developer in flowing over the plate will neither speed up nor slowdown. The terminal velocity is influenced by a great many factors inaddition to the angle of the plate and including such things asatmospheric conditions, the nature of the surface being developed, thenature of the developer material, the strength of the electrostaticcharge pattern on the plate, and the like. In practical situations,however, it has been found that these factors play a relatively minorrole as compared with the plate angle.

It should be appreciated that although only a single embodiment of anautomatic apparatus incorporating and showing the principles and astructure of constant velocity development in accordance with theprinciples of this invention is included herein, there is no intentionto be limited to the particular showing but instead FIG. 1 is forillustrative purposes only and it is intended to en.- compass broadlymethods and apparatus including the principles of constant velocitydevelopment as illustrated and as will be readily apparent to thoseskilled in this art.

In accordance with this invention it has been found that for optimumdevelopment, developer should flow at a constant velocity across thesurface being developed. This type of flow produces a dense image whichis uniform throughout. Further, as will appear more fully in thediscussion which follows, the preferred velocity appears to be thatminimum rate of speed at which blocking (as will be discussed) does notoccur. To more fully appreciate how speed relates to angle ofinclination of the surface being developed, FIG. 2 is discussed below. I

FIG. 2 is a graph showing the relationship between terminal velocity andangle for an electrostatic image bearing selenium xerographic plate anda conventional xerographic cascade developer comprising 1.1% Type 10Toner and 98.9% standard black carrier, available from Haloid XeroxInc., Rochester, New York. Terminal or other developer velocities may bereadily measured by adding a few light-colored particles to thedeveloper and then making a time exposure photograph of the flowingdeveloper when illuminated by a flashing stroboscopic light. Eachlight-colored particle will photograph as a series of distinguishabledots and the spacing of these dots is a measure of developer flowvelocity. Other methods of velocity measurement may also be used.

As shown in FIG. 2 the angle of repose for an uncharged seleniumxerographic plate with the above indicated developer materials isapproximately l6.5.' In other words, if a layer of developer is placedon top of a horizontal uncharged (non-image bearing) plate which is thenslowly tipped, the developer will not start to flow until the platereaches an inclination of about 16.5 At angles somewhat less than theangle of repose, developer will flow over the xerographic plate if it isapplied to the plate with an initial vvelocity. However, at theseangles, developer flow tends to be unstable and terminal velocity is notan accurately reproducible function of inclination.

It can also be seen from the curve in FIG. 2 that for a xerographicplate bearing an electrostatic latent image the terminal velocity versusplate inclination curve starts at about 18, which is a somewhat greaterangle than the angle of repose for an uncharged plate. Developer willflow at angles between 16.5 and 18 but the flow is locally unstable andcarrier beads will stick to the xerographic plate in certain imageareas. As the plate angle is increased past 18 it can be seen that theterminal velocity increases very rapidly, indicating that the developerwill rapidly accelerate at high plate angles unless it meets or is fedto the plate at a correspondingly high velocity. The terminal velocityversus plate inclination curve for an uncharged plate is substantiallythe same as that shown for an image bearing plate, except at anglesclose to the angle of repose where stable flow without bead sticking maybe exhibited by the uncharged but not the charged plate.

Table I is illustrative of the variations in angle of repose which areassociated with various developer compositions and plate surfaces. Theplate surfaces are plain aluminum, plain aluminum with a 20 micronselenium coating, grained aluminum as, used in lithography, and grainedaluminum with a 20 micron selenium coating. Obviously, the uncoatedaluminum materials are not xerographic plates at all, and only theselenium coated plain aluminum corresponds to a normal xerographicplate. The developer compositions are represented by six different typesof carrier materials, each taken both without any toner and with 2%standard toner. Obviously again, the data on untoned carriers are purelyfor comparative purposes, since these materials are not per sexerographic developers. All listed materials are products of HaloidXerox Inc., Rochester, New. York. The first four carriers comprise glassbeads with various surface coatings, where as the last two comprisegraded sand with different coatings. It can be seen that the angle ofrepose with a normal selenium xerographic plate, standard carrier, and2% toner concentration is 14.5 rather than 16.5 as found in connectionwith FIG. 2 for a more conventional 1.1% toner concentration. Thus itcan be seen from Table I that the angle of repose depends on thexerographic materials employed, but only to .a relatively slight degree.

TABLE I Angles of Repose for Several Carriers on Various Surfaces Angleof Repose (Degrees) Carrier Untoned Beads 2% Toner on Beads Al Al-l- GrGr Al Al+ Gr Gr Al Al+ Al AH- Standard 20 22 22 i 20 16.5 14.5 14.3 14.8F 27. 5 28 26. 5 26. 5 20 18. 5 19 18 beads 16 17. 5 16. 5 17 14. 5 i11. 5 14 11 FC-2 on 20-40 mesh sand 24 23. 5 23. 5 24 18. 5 18. 5 19'17. 5 -2 on 2030 mesh sand 24 26 24 24. 18 21. 5 19. 8 l0. 5

Legend: +=With 20 selenium coating. Al=A1uminum sheet. Gr A1 Grainedaluminum sheet.

, Developer flow velocity has been found to be a very important factorin influencing the quality and efficiency of cascade development. Athigh flow velocity it has been found that the developer materialactually scrubs deposited toner off the plate surface. In prior forms ofxerographic apparatus the developer has been applied to a xerographicplate in such a manner that it rapidly accelerated thereafter. Thus, thedevelopment initially effected by the developer material while travelingslowly has been largely counteracted by the undeveloping or erasingeffect of the developer as it speeds up. As the developer flow velocityis decreased, however, it is found that development efficiency increasesand much denser images are obtained. It has also been found that thereis a minimum developer flow velocity which must be maintained. When thisspeed is not maintained, occasionally carrier beads as well as tonerparticles are attached to the xerographic plate by the forces associatedwith the electrostatic image thereon. Sticking beads are veryundesirable because they cause deletions as well as damage to thexerographic plate during image transfer. Sticking beads per se can beavoided by such expedients as forming the beads of magnetic material andremoving them with a magnet, but this does not overcome the problem ofdeletions or small undeveloped areas caused by the sticking beads. Theminimum acceptable developer velocity is influenced by a number offactors such as the carrier particle size and triboelectric properties,the strength of the electrostatic latent image on the surface beingdeveloped, and the ratio of carrier to toner, since this affects theelectrostatic charge on the carrier particles. In general, however, ithas been found that the sticking is associated with plate inclinationswhich are less than or close to the angle of repose and with thedeveloper velocities associated therewith, Whereas bead sticking isgenerally absent at plate inclinations a few degrees greater than theangle of repose and with developer velocities corresponding to theterminal velocities associated with such inclinations. In examining FIG.2 in this connection it is apparent that the optimum angle forconventional xerographic materials is in the general area of 19 whichcorresponds to a terminal velocity for a developer of about 28 inchesper second. This angle is just sufficiently greater than the absoluteminimum angle of about 18 to provide an adequate margin of safetyagainst bead sticking. It has been observed that a relatively high anduniform image density is obtained with constant velocity development atplate angles between 18 and 20, whereas, there is a noticeable fall offin image density at a 25 inclination. It will be appreciated that priorxerographic development methods have typically involved plate angles inthe order of 45.

In accordance with the present invention, the apparatus of FIG. 1 iscapable of being adjusted and is adjusted to provide a developer flowvelocity over the entire area of plate 12 subject to developmentsubstantially equal to the optimum velocity. This adjustment isessentially made in two steps. The first step is to choose the properinclination for the upper surface of plate 12 as determined, forexample, from FIG. 2. Adjustment mechanism is not shown in the figurebecause ordinarily the plate angle need not be changed and is thereforeinitially designed into the apparatus. The second step is to adjust thevelocity at which the developer is applied to the plate to substantiallycoincide with the terminal velocity for the particular plate angles andmaterials employed. Where the initial velocity is equal to the terminalvelocity, the developer will continue to flow across the surface of theplate at an unchanging velocity which has also been chosen as theoptimum velocity and which will provide uniform, dense and higherquality images than have heretofore been produced. To a firstapproximation the initial developer velocity is equal to that whichwould be reached by the developer in falling through a vertical distanceequal to the height of chute 31 and curved section 32. This free-flowvelocity is given by the relation V: 8% where V is the velocity in feetper second and h is the chute height in feet. The actual velocity issomewhat less than this theoretical velocity because of frictionalefiects in chute 31 and along curved section 32. Again, chute 31 is notshown as being adjustable because its configuration is generally setwhen the apparatus is designed and need not be changed thereafter. Whenmaking initial adjustments of chute 31 and curved section 32, it isdesirable to make stroboscopic photographs of the flowing developer bythe procedure described above. graph shows the developer to beaccelerated as it passes across the plate, the initial velocity is toohigh and chute 31 should be shortened somewhat. photograph shows thedeveloper to be decelerated, the initial velocity should be decreased bylengthening chute 31. Obviously other measuring techniques may be used.

If the photo- Conversely, if the While the invention has been describedin connection In particular, it is What is claimed is: 1. A xerographiccopying machine comprising, at least two axially rotatable paraxialspaced cylindrical elements,

the axes of said elements being horizontal, an endles flexiblexerographic plate supported over said cylindrical elements,

said plate being supported in the configuration of. straight linesegments joined by part circular arcs,

an upper segment forming an oblique angle with the horizontal and alower segment,

charging means to charge the outer surface of the lower segment of thexerographic plate while said plate remains stationary,

transparent means to support an original subject to be reproduced facedownward,

means to illuminate said subject while supported,

a projection lens,

first mirror means positioned and adapted to direct the light from saidsubject through said projection lens, second mirror means positioned andadapted to'direct the light from said projection lens through saidcharging means into focus on the lower surface of said plate while stillstationary, means to advance the exposed portion of the xerographicplate to the upper segment position only, means to flow cascadeelectrostatic image developer material over the outer portion of theupper segment of said plate, and means to transfer from the xerographicplate to a support material the developed image produced by flowing saiddeveloper material. 2. A xerographic copying machine comprising, atleast two axially rotatable paraxial spaced cylindrical elements,

the axes of said elements being horizontal, an endless flexiblexerographic plate supported over said cylindrical elements,

said plate being supported in the configuration of straight linesegments joined by part circular arcs, an upper segment forming anoblique angle with the horizontal and a lower segment, charging means tocharge the outer surface of the lower segment of the xerographic platewhile said plate remains stationary, transparent means to support anoriginal subject to be reproduced face downward, means to illuminatesaid subject while supported, a projection lens, first mirror meanspositioned and adapted to direct the light from said subject throughsaid projection lens, second mirror means positioned and adapted todirect 8 the light from said projection lens through said charging meansinto focus on the lower surface of said plate while still stationary,means to advance the exposed portion of the xerographic plate to theupper segment position only, means to flow cascade electrostatic imagedeveloper material over the outer portion of the upper segment of saidplate, means to transfer from the xerographic plate to a supportmaterial the developed image produced by flowing said developermaterial, and means to clean residual developer material from thexerographic plate after image transfer therefrom and before reusethereof. 3. A xerographic copying machine comprising, two axiallyrotatable paraxial spaced cylindrical elements,

the axes of said elements being horizontal, an endless flexiblexerographic plate supported over said cylindrical elements,

said plate being supported in the configuration of two straight linesegments joined by part circular arcs, the upper segment forming anoblique angle with the horizontal, charging means to charge the outersurface of the lower segment of the xerographic plate while said plateremains stationary, transparent means to support an original subject tobe reproduced face downward, means to illuminate said subject whilesupported, a projection lens, first mirror means positioned and adaptedto direct the light from said subject through said projection lens,second mirror means positioned and adapted to direct the light from saidprojection lens through said charging means into focus on the lowersurface of said plate while still stationary, I means to advance theexposed portion of the xerographic plate to the upper segment positiononly, means to flow cascade electrostatic image developer material overthe outer portion of the upper segment of said plate, and means totransfer from the xerographic plate to a support material the developedimage produced by flowing said developer material. 4. A xerographiccopying machine comprising, two axially rotatable paraxial spacedcylindrical elements,

the axes of said elements being horizontal, an endless flexiblexerographic plate supported over said cylindrical elements,

said plate being supported in the configuration of two straight linesegments joined by part circular arcs, the upper segment forming anoblique angle with the horizontal, charging means to charge the outersurface of the lower segment of the xerographic plate while said plateremains stationary, transparent means to support an original subject tobe reproduced face downward, means to illuminate said subject whilesupported, a projection lens, first mirror means positioned and adaptedto direct the light from said subject through said projection lens,second mirror means positioned and adapted to direct the light from saidprojection lens through said charging means into focus on the lowersurface of said plate while still stationary, means to advance theexposed portion of the xerographic plate to the upper segment positiononly, means to flow cascade electrostatic image developer material overthe outer portion of the upper segment of said plate,

9 means to transfer from the xerographic plate to a support material thedeveloped image produced by flowing said developer material, and meansto clean residual developer material from the Xerographic plate afterimage transfer therefrom and before reuse thereof.

10 Young Aug. 23, 1955 Ebert Apr. 12, 1960 Limberger Aug. 30, 1960Limberger Feb. 21, 1961 Bird May 21, 1961 Limberger Oct. 24, 1961Blakely Oct. 31, 1961 Schwertz Mar. 6, 1962 Greig Sept. 4, 1962 McNaneyJan. 1, 1963 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No $146,688 September l 1964 Harold Ejwclarkwet all.

It is hereby certified, that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, lines 58 and 59 for "FIG. 2 is a graph relating developervelocity to xerographic cascade development methods.,'' read It isstillflalfurther object to provide improved xerographic cascadedevelopment methods, column 5 TABLE I ninth column, line 6 thereof. vfor "105 read 205 Signed and sealed this 13th day of April 1965;.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J BRENNER A-ttesting Officer Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No3 146 688 vSeptember l 1964 Harold Clark .et ala It is hereby certifiedvthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 1, lines 58 and 59, for "FIG. 2 is a graph relating developervelocity to xerographic cascade development methods." read It isstillwanfurtherv object to provide improved xerographiccascade,developmentmethods, column 5 TABLE I ninth column line 6thereof. for "105-" read 2005 m Signed and sealed this 13th day of April1965.

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Auesting Officer Commissioner ofPatents

1. A XEROGRAPHIC COPYING MACHINE COMPRISING, AT LEAST TWO AXIALLYROTATABLE PARAXIAL SPACED CYLINDRICAL ELEMENTS, THE AXES OF SAIDELEMENTS BEING HORIZONTAL, AN ENDLES FLEXIBLE XEROGRAPHIC PLATESUPPORTED OVER SAID CYLINDRICAL ELEMENTS, SAID PLATE BEING SUPPORTED INTHE CONFIGURATION OF STRAIGHT LINE SEGMENTS JOINED BY PART CIRCULARARCS, AN UPPER SEGMENT FORMING AN OBLIQUE ANGLE WITH THE HORIZONTAL ANDA LOWER SEGMENT, CHARGING MEANS TO CHARGE THE OUTER SURFACE OF THE LOWERSEGMENT OF THE XEROGRAPHIC PLATE WHILE SAID PLATE REMAINS STATIONARY,TRANSPARENT MEANS TO SUPPORT AN ORIGINAL SUBJECT TO BE REPRODUCED FACEDOWNWARD, MEANS TO ILLUMINATE SAID SUBJECT WHILE SUPPORTED, A PROJECTIONLENS, FIRST MIRROR MEANS POSITIONED AND ADAPTED TO DIRECT THE LIGHT FROMSAID SUBJECT THROUGH SAID PROJECTION LENS, SECOND MIRROR MEANSPOSITIONED AND ADAPTED TO DIRECT THE LIGHT FROM SAID PROJECTION LENSTHROUGH SAID CHARGING MEANS INTO FOCUS ON THE LOWER SURFACE OF SAIDPLATE WHILE STILL STATIONARY, MEANS TO ADVANCE THE EXPOSED PORTION OFTHE XEROGRAPHIC PLATE TO THE UPPER SEGMENT POSITION ONLY, MEANS TO FLOWCASCADE ELECTROSTATIC IMAGE DEVELOPER MATERIAL OVER THE OUTER PORTION OFTHE UPPER SEGMENT OF SAID PLATE, AND MEANS TO TRANSFER FROM THEXEROGRAPHIC PLATE TO A SUPPORT MATERIAL THE DEVELOPED IMAGE PRODUCED BYFLOWING SAID DEVELOPER MATERIAL.